Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 261155 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 755 AM EDT Thu Apr 26 2018 .UPDATE... Issued at 755 AM EDT THU APR 26 2018 Fog and low clouds were affecting much of the area early this morning, but will dissipate during the morning. However, higher clouds associated with the next weather system will be on the way in and probably keep sunshine limited today. Otherwise, early morning temperatures have been blended into the forecast, with no real impact. && .SHORT TERM...(Today through Friday) Issued at 419 AM EDT THU APR 26 2018 The low pressure system which brought rain to the area over the last few days has finally departed to the northeast. There is no appreciable change in air mass in its wake, and with clouds trying to break up at times, the cooling of the already damp surface air has led to fog development in many areas. The fog should dissipate on Thursday morning as temperatures start to climb. However, clouds with the next weather system will be on the way in, and only allow for very limited sunshine. Early this morning, this next low pressure system was centered over AR and northern MS. It will track eastward, passing to our south late today and this evening. Models have settled on a solution bringing light rain to our southern and southeastern counties, with more significant rain further to the south and east. Have continued with a 60-70% POP near the TN and VA borders, tapering to less than 20% north of I-64. This system turns northeast on the east side of the Appalachians as it pulls away tonight. Most of the forecast area can then expect a dry day on Friday. With no appreciable change in air mass, and clouds breaking up, temperatures should be milder. A cold front will approach from the northwest late in the day. Moisture will be very limited along the front, and the prospect for precip is small. The GFS does have some showers developing in shallow convection in our northwest counties toward evening, but the NAM and ECMWF keep precip to our north. In a compromise, have used just a 20% POP north of I-64 late in the day. .LONG TERM...(Friday night through Wednesday) Issued at 419 AM EDT THU APR 26 2018 Large scale troughing will be in place across the Ohio Valley to start off the period Friday night into Saturday, deepening as a closed low develops and rotates through the Great Lakes region. This low is expected to exit east of the Great Lakes by Sunday evening/night, with rising heights taking hold across Kentucky as upper level ridging begins to move into place. This ridging will encompass much of the eastern Conus by Tuesday. Both the ECMWF and GFS are in good agreement about large scale troughing across the western half of the Conus during this time, with a upper level low developing within the trough axis and quickly rotating SE, drastically lowering heights across the western most states. As this closed low makes the shift northeastward towards the Central Plains during the day Wednesday, heights across the central U.S. will lower quickly. The closed low will eventually weaken and become absorbed into the trough again, but not before heights begin lowering across Kentucky during the day Thursday. As for sensible weather, an area of precipitation will be associated with a surface low pressure system moving through the Great Lakes Friday night and Saturday. While there is still some uncertainty on the exact expanse and track of this precipitation swath, the ECMWF, NAM80, and ECMWF show the main area of precip north of the Ohio River, expanding into far SE KY during Saturday afternoon under more W to NW flow. As such, kept mention of pops out of CWA Friday night through the first part of the day Saturday, with just slight chance pops for Saturday afternoon. After this system moves out, an expansive area of surface high pressure will take hold across the region for the remainder of the weekend and well into mid week next week. Each day that ridging and high pressure are in place means the airmass will modify warmer, especially as southerly winds set in. Highs on Sunday will be around 60 degrees under NW flow...however by Monday sunny conditions combined with a more Srly flow will boost afternoon temps into the low 70s in many locations. In fact, current forecast has temperatures possibly reaching 80 degrees by Tuesday in a few locations. The same will be true for Wednesday as well. By late Wednesday afternoon and into Thursday, clouds will be on the increase as a cold front begins to near the region from the west, following the greatest height falls aloft. Despite clouds, the strong Srly flow will still boost temps to near 80 for highs on Thursday. A few pop up showers will be possible as early as Wednesday afternoon ahead of this system, so kept in the slight chance pops that the Superblend gave over portions of the western CWA during this time. These will quickly diminish in the evening. The main line of precip associated with this storm system will then begin impacting western Kentucky during the day Thursday. This will result in generally slight chance pops across our western CWA throughout the day, increasing just past the forecast period as the system continues on its eastward track towards JKL. && .AVIATION...(For the 12Z TAFS through 12Z Friday morning) ISSUED AT 755 AM EDT THU APR 26 2018 Fog and low clouds were affecting most of the area early this morning. They are expected to dissipate by late morning, giving way to VFR conditions. Clouds will then lower again over southern and southeastern Kentucky during the afternoon, with rain likely developing. Conditions should be low end VFR by late in the day, perhaps hitting MVFR in some locations. The light rain and borderline VFR/MVFR conditions should then last into the evening in southeast Kentucky, probably lowering into MVFR territory overnight. Meanwhile, higher ceilings and dry weather should prevail further to the northwest. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...HAL SHORT TERM...HAL LONG TERM...JMW AVIATION...HAL

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